1. Field of the Invention
The present invention relates generally to radar systems. More particularly, the present invention relates to an encoder circuit which receives radar video data and encodes the radar video data to provide Non-Return-To-Zero-Level (NRZL) Data which is then supplied to an encryption unit for encryption by the encryption unit.
2. Description of the Prior Art
The military often locates a ground based radar at a site which is remote from the receiving station where the data from the radar is processed and then observed on radar video display screen. The distance between the ground based radar and the receiving station may be several miles which often requires that the radar data be transmitted over public lands via, for example, fiber optic cables. Since data from the ground based radar generally includes classified information there is a need to protect the data during the transmission thereof over the fiber optic cables linking the ground based radar to the receiving station. This requires that the radar data, which is generally in an analog format, be digitized for compatibility with digital formatted encryption units, such as the KG194 encryption unit, currently being utilized by the United States Armed Forces.
The encrypted data is next transmitted via the fiber optic cable to the receiving station where it is un-encrypted by a second encryption unit and then provided in a digital format for processing and then display on a radar video display screen. The digitized radar data is then converted to an analog format which is compatible with the radar video display screen.
It is therefore an object of the present invention to provide to digitize analog radio video data into an NRZL data format which is compatible with an encryption unit.
It is another object of the present invention to generate a frame synch signal in response to a radar trigger pulse received from a radar.
It is yet another object of the present invention to provide a serial data stream which includes a frame sync signal, synchro data and digitized radar video data.
Other objects, advantages and novel features of the present invention will become apparent to those skilled in the art after reviewing the following detailed description of the preferred embodiment in conjunction with all of the figures of the drawings.